A subpleural nodule [Figure 1] was noted in the posterior segment of the left upper lobe at a complete autopsy performed in a 54-year-old female with a long-standing bipolar disorder. It measured 2 cm in diameter and was well-circumscribed, pale yellow, soft to firm with slightly fasciculated cut surface. Histopathology [Figure 1]b and [Figure 1]c revealed a proliferation of spindle-shaped cells, arranged in fascicles and whorls with numerous psammoma bodies. The cells had bland nuclei with scant to moderate cytoplasm and poorly delineated outlines. No mitosis or necrosis was noted. These findings were suggestive of psammomatous meningioma; immunohistochemistry showed a strong positivity for vimentin and epithelial membrane antigen. Central nervous system examination was normal; hence, metastatic meningioma was ruled out.

This tumor, diagnosed as a primary pulmonary meningioma (PPM), is an example of an ectopic, extracranial, or extraspinal location of meningiomatous tumors. They account for 1%–2% of all primary meningiomas and are predominantly seen in the head and neck regions at various sites and in the paraspinal soft tissues.[1] PPM is an extremely rare entity and since its first description in English literature by Kemnitz et al. in 1982;[2] only about 50 cases have been reported.[3] It should be noted that the lungs are the most common location for metastatic meningiomas, which can occur after varying periods of time (months to years) after excision of the intracranial tumors. Hence, the single most important criterion is the absence of any intracranial or intraspinal lesion, as seen in this case after a complete autopsy. The patient also had no history of any previous operation.

The origin of PPMs is not ascertained. The hypotheses include origin from the embryonic remnants, meningothelial differentiation of subpleural pluripotential mesenchymal cells, or from the minute pulmonary meningothelial-like nodules (MPMNs). The MPMNs are small (100 μm to 0.3 cm) reactive interstitial cellular lesions that often develop in the background of chronic lung disease and have histological, immunohistochemical, and ultrastructural characteristics similar to meningothelial cells; origin of PPMs from MPMN is an attractive proposition.[4] Our patient did not have any lung disease and there were no MPMNs. The lesion was solitary and asymptomatic.

Most of the PPMs have been seen as asymptomatic parenchymal “coin” lesions, ranging in size from 0.4 to 6.5 cm with a mild preponderance in elderly women.[5] However, some can be endobronchial, multiple, or symptomatic due to chest pain or hemoptysis.[6] A majority of the PPMs have been benign and show varies histomorpholgy like their central nervous system (CNS) counterparts; usually psammoma bodies are commonly encountered.[5],[6] Hence, a video-assisted wedge resection is ideal for peripheral lesions, whereas lobectomy is suitable for lesions located in the central lung. No recurrences were observed in long-term follow-up of these patients with benign PPMs. Very infrequently, some tumors may show atypical features or may be overtly malignant with metastases.[5],[6] These are usually larger in size and require aggressive therapy, and owing to rarity of such lesions, the prognosis is not exactly known. It would be important to note that PPMs are rare lung masses and more likely to be misdiagnosed and overtreated.

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